Lightning arrester with ionization chamber



April 2, G p CAPART 1,996,321-

LIGETNING ARRESTER WITH IONIZATION CHAMBER Filed March 5, 1931 3 Sheets-Sheet 1 Fig.1

I2 4 Z .771 #52770/1 :Xf

April 2, 1935. G. P. CAPART LIGHTNING ARRESTER WITH IONIZATION CHAMBER Filed March 5, 1931 3 Sheets-Sheet 2 April 2, 1935.

G. P. CAPART LIGHTNING ARRESTER WITH IONIZATION CHAMBER Filed March 5, 1931 3 Sheets-Sheet 3 Patented Apr. 2, 1935 LIGHTNING ABBESTEB. WITH IONIZATION HAMBEB Gustave Paul Capart, La Varennc, St. Hilaire, France, assig'nor to Socit a Responsabilit Limite dite: Le Parafoudre Universel Corona,.

Paris, France Application March 5, 1931, Serial No. 520,440 In France March 18, 1930 scrum.

The object of the present invention is a lightning arrester provided with an ionization chamber designed so as to cause the efliux of electric charges due to supertension, that is to say to steep front waves and to the waves of great amplitude which occur in electric wiring systems. The apparatus is more specially intended for medium tension systems (a few thousand volts). Its functioning is based on the use of an ionization chamber which, in a manner, artificially creates a corona eifect.

n the attached drawings three forms of embodiment of the lightning arrester, which forms the subject matter of the invention, have been shown in a diagrammatic. form and solely as examples:

Figure 1 is the diagram of an existing device;

Figure 2 is the diagram of the new apparatus;

Figure 3 is a part section of an example of an embodiment of the apparatus;

Figure 4 is a larger scale sectional diagram showing the arrangement of the ionization chamber;

Figure 5 is a section of a different arrangement of the ionization chamber;

Figure 6 is another different embodiment of the ionization chamber and of its spark gap discharge device in section.

The existing device, shown in Figure 1, is constituted by an inductance I shunted by a resistance 2; one of the terminals of the inductance is grounded through a condenser 3; the otherterminal of the said inductance is led to the lightning arrester device proper l, which is grounded.

The new lightning arrester, which forms the subject matter of the invention is diiferentiated from existing devices by the fact that condenser 3 is shunted by an ionization chamber P which artificially creates a corona efiect, and through this chamber the charge due to supertension will be led away. This arrangement is seen in Figure 2.

In the example of an embodiment shown in Figure 3, self inductance I, mounted on suitable insulating supports 5 and 6, surrounds the tubular condenser 3, the metallic armature I, cylindrical in shape, of which is separated by a tube, made of a dielectric substance 8, from metallic rod 8 which constitutes the second electrode grounded at I8. Resistance 2 is in the form of a crown fitted at the end of tube or electrode I and is connected to that terminal of seli. inductance I which leads to the output conductor II. The opposite terminal of the self inductance is connected, through the input conductor I2, to electrode I and penetrates into the ionization chamber P shown to a larger scale in Figure 4.

The ionization chamber P is constituted by washers I3 made of a more or less resistant or semi-conductive substance (carborundum, for instance, in the case of comparatively high tensions and aluminum for low tensions etc., arranged in the tube 8 and kept apart from one another by insulating spacing rings It. The inner surface of these inserted rings I4, which constitute the ionizing elements, is coated with a radioactive layer I5. The whole assembly, including washers I3, rings I4 and their layer of radioactive matter l5, is located in tube 8 and held between the metallic electrodes I and 8 of condenser 3, constituting the ionizing chamber which supplies the means of artificially causing a corona effect which makes it possible to dissipate the charges due to supertension.

In the example of an embodiment shown in Figure 5, the parts already described in the preceding fiigures, bear the same reference numbers as in those figures. V

In this figure the self inductance has been designated by I, the outer end inner electrodes of the tubular condenser by I and 9, these electrodes being separated by dielectric 8; the washers oi the ionization chamber by I3, these washers being kept apart from one another by the inserted insulating rings I4, their innersurface being coated with a radioactive layer I 5. The input collector, which connects the self inductance I to armature I of the condenser, has been designated by I2.

In this modified embodiment, the ionization chamber has been extended on the side opposite to armature 8 and in this extension has been located a spark gap discharge device which possesses an adjustable and automatically variable sparking distance, this spark gap discharge device being constituted by an electrode I6 fitted in the center of a flange I! provided with holes I8 and by an electrode I9 screwed into a movable disc 20 arranged as a valve resting on a seat 2|. Seat 2| isseparated from flange I1 by a spacing insulating sleeve 22 the inner surface of which is coated with radioactive substance I5. Disc 20 is pressed against seat 2| by a spiral spring 23 which bears on a flange 24 provided with holes 25, the center portion of this flange being designed to serve as a guide to electrode I8 the rear portion of which, in the form of a screw head 26,'is located opposite the central hole 21 provided at the rear end of armature I of the lightning arrester. Disc 2! is separated fromthe flange 24 by an insulating sleeve 29.

The improved device, which can be applied to high tension wiring systems, functions as follows:

When supertension occurs this causes the striking of an are which jumps between electrode l9 (connected to the input conductor 52 through disc 29, spring 23, flange 24 and conducting sleeve 29) to electrode i3, this discharge being aided by the ionization of the spark gap discharge chamber, which ionization is determined by the radioactive substance 85 which coats the spacing sleeve 22; from electrode i3, discharge continues towards armature 9 through the ionization chamber (described in Figures 1 to 4) constituted byv washers i3 and inserted rings M. The ,deflagration which occurs at the moment of the discharge causes a sudden expansion of the air confined in the space contained in the ionizing chamber and its extension, which space is closed by disc 29; this disc is driven back violently together with electrode IS. The sparking distance separating the electrodes l6 and i9 is thus increased causes the extinction of the arc the quenching of which is aided by the air eddy in the ionizing chamber. At the same moment as the arc is extinguished, electrode l9 returns to its original position together with disc 29 which seals the ionizing chamber anew and the apparatus is ready to function again. The initial sparking distance between electrodes l6 and 19 may be adjusted by screwing the latter electrode more or less into disc 29.

In the example of an embodiment illustrated in Figure 6, the parts already described have.

ignated l2 and the movable disc which forms the valve and rests on seating 2|, by 29.

In this modification of the embodiment, the ionization chamber is constituted by metallic washers 3| strung over an insulating tube 32 and separated from one another by insulating washers 33, 34; each set of three insulating washers presents an annular groove lined with radioactive substance 35. The end washers 36 are thicker than washers 3| and constitute cheeks tightened between conducting parts 31 and 38, the latter being solid with armature 9 of the condenser. In the axial hole of tube 32 is a rod 39 connected with armature 9 of the condenser and conducivev (through an antenna effect) to ionization in the ionization chamber. The rod 39, combined with the ionization chamber, has the efiect. of considerably augmenting the conductivity of the air or of the ionization gas in the vicinity of the electrodes, and as a consequence to lower the sparking potential and to facilitate the passage of the sparks.

The ions emitted by the radioactive salts thus become the movable armatures of a condenser of which the rod 39 is the other armature, while The movable equipment of the variable sparking distance spark gap discharge device is constituted by a rod 43 provided with a screw thread and terminated by a slotted head 25 which is accessible through port 21 provided in the outer electrode I of the condenser. The threaded rod 93, which may be more or less screwed into disc 29 acting as a valve, is terminated, on the side towards ring 92, by a disc 39 acting as an electrode, in front of which disc is an insulating screen fixedly secured on aforementioned rod 93. Screen (i5 cooperates with an insulating diaphragm 99 (at the moment when the spark' gap discharge de ice movable portion moves backwards) to diaphragm the ionized space separating disc 99 from ring 32 when the apparatus functions owing to a discharge. On the other hand, screen 95 constitutes a baflie and increases the sparking distance which separates electrodes 99 and 42, when the moving equipment of the spark gap moves backwards. On the rear of the valvedisc 29 is a resistant sleeve 47 separated from threaded rod 43 by an insulating tube 43. Threaded rod 43 which can slide (by its smooth portion in front of screw head 26) in guidingpart 24, bears a contacting disc 49 upon which spring 23 acts. When the apparatusis idle and is not functioning, disc 49 is in contact with a contacting ring 59 perforated with holes 5! and connected, by means'of connecting piece 52, to the input conductor l2 and the outer electrode 1.

Parts 42, 46, 2|, 59, 29 and the left hand end of electrode 1 are separated from one another by insulating sleeves 53, 54, 55, 56, 51 and 58.

The improved device which, by suitable adjustment can be applied to wiring systems of very difierent tensions, functions as follows:

When supertension occurs an arc is struck, jumping between electrode 44 (connected with the input conductor H by threaded rod 43, disc 99, ring 59 and conductor 52) and electrode 42.

' The striking of this arc is aided by the ionization caused by the radioactive material of the spark gap chamber; from electrode 42 the discharge proceeds towards armature 9, through part 31, the new ionization chamber (constituted by washers 3i and the insert parts 33 and 34) and part 38. The deflagration which occurs at the moment of discharge causes the sudden expansion of the air confined in the space enclosed in the ionization chamber and in the spark gap chamber, this space being sealed by disc 29; this disc is then violently driven backwards and draws 43 and diaphragm 46, which causes the extinction of the arc, the quenching of which is aided tion chamber and the spark gap chamber and the apparatus is ready to function anew.

The different forms of embodimentdescribed above are supplied only as indications, the details of construction may be modified without departing from the subject matter of the invention.

What I'claim is 1. A condenser comprising two concentric cylindrical armatures separated by a tube of a dielectrical substance, said tube containing an ionization chamber connected, on the one hand, to the outer armature and, on the other hand, to the inner armature.

2. A device according to claim 8, comprising a supplementary, adjustable and automatically variable sparking distance discharge device fitted in an extension of the ionization chamber, one of the two electrodes of said discharge device being integral with a movable sealing disc normally closing the ionization chamber, which disc is adapted to be moved from its normal rest position by the air expanding under the electric discharge so as to increase the distance between said electrodes when said discharge occurs.

3. A device according to claim 8, comprising a supplementary, adjustable and automatically variable sparking distance discharge device fitted in an extension of the ionization chamber, one of the electrodes of said discharge device being controllably threaded into the approximate center of a movable valve-shaped disc; a seat for said disc, and a spring urging said disc against said seat, said electrode being adjusted in spaced relationship to. the other electrode according to the voltage of the system to be protected.

4. In a l :htning arrester, a condenser ionizing structure, the said condenser comprising two concentric cylindrical electrodes, a tube of dielectric material separating said electrodes, and an ionization chamber, the said ionization chamber being contained by said tube and comprising a series of metallic washers, inserted rings oi! insulating material separating said washers, and a layer of radioactive substance covering said rings, the end washers being electrically connected respectively to the inner and outer electrodes of the condenser.

5. In a lightning arrester, a condenser ionizing structure, the said condenser comprising two concentric cylindrical electrodes, a tube of dielectric material separating said electrodes, and an ionization chamber, the said ionization chamber being contained in said tube, and comprising a series of semi-conductive elements, inserted rings of insulating material separating said elements, a layer of radioactive substance covering said rings, the end elements being electrically connected respectively to the inner and outer electrodes of the condenser, a supplementary, adjustable and automatically variable spark-gap discharge device fitted in an extension of the ionization chamber, one of the electrodes 01' said discharge device having the shape of a disc and mounted on a rod controllably threaded into the approximate center of a movable valve-shaped disc, a seat for said valve-shaped disc, resilient means urging the valve-shaped disc against said seat, said disc-shaped electrode being adjustable in spaced relationship to the other electrode acstationary diaphragm with which said screen cooperates to break the are when the movable disc is driven backward by an electric discharge.

6. In a lightning arrester, a condenser ionizing structure, the said condenser comprising two concentric cylindrical electrodes, a tube of dielectric material separating said electrodes, and an ionization chamber, the said ionization chamber being contained in said tube, and comprising a series of semi-conductive elements, inserted rings of insulating material separating said elements, a layer of radioactive substance covering said rings, the end elements being electrically connected respectively to the inner and outer electrodes oi. the condenser, a supplementary, adjustable and automatically variable sparking distance discharge device fitted in an extension of the ionization chamber, one of the electrodes of said discharge device comprising a spring-pressed disc mounted on a rod, a movable valve-shaped disc, into the approximate center 0! which the rod of the spring-pressed disc is adiustably threaded, a seat against which the valve-shaped disc is thereby urged, said electrode being adjusted in spaced relation to the other electrode according to the voltage of the system to be protected and said electrode being connected at rest to the input electrode of the condenser, a damp-v ing resistance movable with said movable electrode, a check crown ring between which and the valve-shaped disc the resistance is inserted at the end of the functioning stroke 0! the movable valve-shaped disc, an insulated disclike screen placed in front of the disclike electrode, and a stationary diaphragm with which said screen is adapted to cooperate to break the are when the movable disc is driven backwards by an electrical discharge. a

7. In a lightning arrester, a condenser ionizing structure, the said condenser comprising two concentric cylindrical electrodes, a tube of dielectric material separating said electrodes, and an ionization chamber, the said ionization chamber being contained in said tube, and comprising a series of semi-conducting elements, inserted rings of insulating material separating said elements, a layer of radioactive substance covering said rings, the end elements being electrically connected respectively to the inner and outer electrodes of the condenser, a supplementary, adiustable and automatically variable spark-gap discharge device fitted in an extension of the ionization chamber, one of the electrodes oi said discharge device comprising a spring-pressed disc mounted on a rod, a movable valve-shaped disc into the approximate center of which the rod of the spring-pressed disc is adjustably threaded, a seat against which the valve-shaped disc is thereby urged, said electrode being adjusted in spaced relation to the other electrode according to the voltage of the system to be protected and said electrode being connected at rest to the input electrode of the condenser, a damping resistance movable with said movable electrode, a check crown ring between which and the valve-shaped disc the resistance is inserted at the end of the functioning stroke of the movable valve-shaped disc, a rod carrying the disclike electrode, said resistance consisting of a sleeve of semi-conductive substance entirely insulated from said rod, and adapted to connect, at the end of the back stroke of said electrode, the valveshaped disc to said check crown, an insulated disclike screen disposed in front of the disclike electrode, and a stationary diaphragm with which said screen cooperates to break the are when the movable disc is driven backwards by an electrical discharge.

. 8. In a lightning arrester, a condenser-ionizing structure, the condenser comprising two concentric cylindrical electrodes, a tube of dielectric material separating said electrodes, the ionizing portion of said structure comprising an ionization chamber contained in said tube and comprising a series of washers of more or less resistance, in-

serted rings of insulating material separating said washers from each other, and a layer of radioactive substance covering said rings, the end washers being connected respectively to the inner and outer electrodes of the condenser.

GUSTAVE PAUL CAPART. 

